In Fukushima, Wild Boar And Escaped Farm Pigs Have Been Canoodling

Rare spotted wild boar observed inside the evacuated area of Fukushima, Japan, indicative of the introgression with domestic pigs following the 2011 disasters. Image courtesy of Hiroko Ishiniwa, 2017.

In the absence of humans, wild boars have ganged up with a population of escaped farmyard pigs and taken over the abandoned radioactive lands of Fukushima, according to a new study published in the journal Proceedings B.

The Fukushima nuclear disaster struck on March 11, 2011, when a catastrophic earthquake and subsequent tsunami hit the Fukushima Daiichi nuclear power plant on the Pacific coast of Japan. Amid the destruction, the power plant suffered three nuclear meltdowns, three hydrogen explosions, and the release of radioactive material across the local environment and beyond. At least 2,313 people lost their lives, while over 100,000 people were forced to evacuate their homes, most of which have not returned.

While an immeasurable tragedy, the human abandonment of large parts of Fukushima has been auspicious for much of the area’s wildlife, which is now free to graze and hunt where they please without the threat of hunters, noisy cars, and other human disturbances. 

Scientists at Fukushima University and Yamagata University have recently studied the genetics of the wild boar that are thriving in this post-disaster wasteland and unearthed some interesting insights. 

“The Japanese government estimates that the boar population has increased from 49,000 to 62,000 boar in 2014 to 2018. We do not have an estimate for 2020-2021 from the prefecture website. But, we expect the numbers to be greater than that,” Donovan Anderson, lead study author from Fukushima University, told IFLScience.  

Boar.
A wild boar spotted inside the mandated evacuation zone in Fukushima, Japan. Image courtesy of Donovan Anderson, 2018.

Reporting their findings this week, the genetic data clearly shows that the wild boar (Sus scrofa leucomystax) have widely bred with domestic pigs (Sus scrofa domesticus) that escaped from farms in the aftermath of the disaster, filling the environment with wild boar-pig hybrids. However, it looks like the domestic pig legacy has been gradually "diluted" over time.

Fortunately, just as other studies have hinted, it appears that the radiation from the nuclear disaster has had no harmful impact on the boars' genetics.

Along with this shift in genetics, the researchers also note that the wild boar population also experienced changes in their behavior. Wild boars are predominantly nocturnal animals, with peak activity at around midnight when they leave their shelter to find food. However, post-accident, the wild boars of Fukushima have turned to a more “diurnal” daytime behavior. 

“The wild boar have adapted to the human abandoned landscapes,” Anderson told IFLScience. “They seem to not fear approaching cars too much and sometimes people, and that’s why we can capture photos so easily. 

“The wild boar here shifted to more diurnal behavior. In other words, inside the evacuation zone, the wild boar are generally more active during the daytime than other boars, which tend to be more nocturnal. This is more than likely because there’s less human disturbances or threats,” he explained.

Over in Eastern Europe, the absence of humans in the Chernobyl Exclusion Zone, the site of the infamous 1986 nuclear disaster, certain wildlife have also bounced back. Some studies of the surrounding land have found that the area holds relatively strong numbers of wolves, wild boars, red foxes, and raccoon dogs. It's also home to 1,000 or so stray dogs which are descended from abandoned pets.


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